import { Utility } from "./utility"

let watermark = {}

let setWatermark = (username, sourceBody) => {
	let id =
		Math.random() * 10000 +
		"-" +
		Math.random() * 10000 +
		"/" +
		Math.random() * 10000

	if (document.getElementById(id) !== null) {
		document.body.removeChild(document.getElementById(id))
	}

	let can = document.createElement("canvas")
	can.width = 160 //设置水印之间的左右间距
	can.height = 80 //设置水印之间的上下间距

	let cans = can.getContext("2d")
	cans.rotate((-20 * Math.PI) / 180)
	cans.font = "15px Vedana"
	cans.fillStyle = "rgba(0, 0, 0, .1)"
	cans.textAlign = "left"
	cans.textBaseline = "Middle"
	cans.fillText(username, can.width / 20, 40)
	cans.fillText(Utility.getCurrentDate(), can.width / 20, 60)

	let water_div = document.createElement("div")
	water_div.id = id
	water_div.className = "watermarkClass"
	water_div.style.pointerEvents = "none"
	water_div.style.background =
		"url(" + can.toDataURL("image/png") + ") left top repeat"
	if (sourceBody) {
		water_div.style.width = "100%"
		water_div.style.height = "100%"
		sourceBody.appendChild(water_div)
	} else {
		water_div.style.top = "3px"
		water_div.style.left = "0px"
		water_div.style.position = "fixed"
		water_div.style.zIndex = "100000"
		water_div.style.width = document.documentElement.clientWidth + "px"
		water_div.style.height = document.documentElement.clientHeight + "px"
		document.body.appendChild(water_div)
	}

	return id
}

/**
 *  该方法只允许调用一次
 *  @param:
 *  @text == 水印内容
 *  @sourceBody == 水印添加的位置，不传就是body
 * */
watermark.set = (text, sourceBody) => {
	const domArr = Array.from(document.getElementsByClassName("watermarkClass"))
	for (let i = 0; i < domArr.length; i++) {
		const element = domArr[i]
		element.remove()
	}
	if (text == "") {
		return
	}
	setWatermark(text, sourceBody)
}

export default watermark
